Biomedical subjects
Publications and source records attributed to Takashi Togawa.
Radio-iodine (131I) therapy has been using in Graves' disease and well differentiated thyroid cancer. The rules of control in the discharge from radio-isotope hospital were notified in 1999 in Japan. Guideline of the 131I therapy in Graves' disease and thyroid cancer were prepared by sub-group of Japanese Society of Nuclear Medicine.
Whether a patient with head and neck cancer has mandibular invasion or not is important in determining the method of resection surgery. But, no modality is adequately reliable when used alone in the evaluation of mandibular invasion. Therefore, to more accurately diagnose mandibular invasion in head and neck cancer, we used a new modality, namely, 99mTc methylene diphosphonate (MDP) or 99mTc hydroxymethylene diphosphonate (HMDP) and 201Tl chloride dual isotope single photon emission computed tomography (Tc/Tl SPECT). The aim of this study is to disclose the usefulness of Tc/Tl SPECT in the assessment of mandibular invasion by head and neck cancers. 99mTc-MDP or -HMDP SPECT (Tc SPECT)s and 201Tl chloride SPECT (Tl SPECT)s were performed in 34 patients with suspected mandibular involvement of head and neck cancer. Thirty of 34 cases underwent both TcMTl SPECT and CT examination. Tc/Tl SPECT fusion images were obtained using the Automatic Registration Tool (ART, TOSHIBA, Japan) system. In the diagnosis of mandibular invasion on Tc/Tl SPECT fusion images, a problem was that the range of Tc and Tl uptake was changed by the condition of display used in the reconstruction and expression of the images. Then, prior to clinical evaluation, to reveal the most appropriate upper window level for display, a phantom study was performed. In a clinical study, the upper window level was set at 40 or 50%, which were verified to be the proper values in the preliminary study. The diagnostic accuracy obtained using Tc SPECT, TcMTl SPECT and CT was compared with the histopathological findings. Tc/Tl SPECT at 40 and 50% upper window level had higher specificity, accuracy, and positive predictive value (73.3%, 85.3%, 81.8%) than Tc SPECT alone (21.4%, 67.6%, 64.5%) and higher sensitivity and negative predictive value (94.7%, 91.7%) than CT (70.6%, 72.2%) for detecting mandibular invasion. Tc/Tl SPECT was a useful diagnostic procedure for the assessment of mandibular invasion by head and neck cancers.
The aim of this study is to reveal the usefulness of semi-quantitative assessment using 201Tl chloride (Tl) single photon emission computed tomography (SPECT) (Tl SPECT) to evaluate the effectiveness of radiotherapy in 15 patients with oral cavity squamous cell carcinma (SCC). Fifteen patients were diagnosed with SCC by biopsy. All 15 patients enrolled in this study were planned to undergo preoperative radiotherapy with or without chemotherapy using carboplatin (CBDCA) and received reduction operation. Tl SPECTs were performed 15 minutes after intravenous administration of 111 MBq 201Tl chloride. Regions of Interest (ROI) were set up around tumor (T), and non-lesion (N) at the part of contralateral scalp at the height of the cerebellum. The ratios of mean counts in ROI of the tumor to those in non-lesion were measured as pre- and post-treatment T/N ratios (pre T/N, post T/N). Furthermore, reduction rate (RR) was obtained by calculating [(pre T/N - post T/N)/(pre T/ N)] x 100%. Each parameter (pre T/N, post T/N, and RR) was compared to histopathological grade of surgical specimen based on the Oboshi and Shimosato classification (grade I-IV). RR showed significantly higher values in grade III and IV than in grade I and II (p = 0.0008). In conclusion, semi-quantitative assessment using Tl SPECT, especially calculating RR, is useful to evaluate the effectiveness of preoperative radiotherapy.
OBJECTIVE: The aim of this study is to examine the correlation between tumor angiogenesis and response to preoperative radiotherapy evaluated using 201Tl single photon emission computed tomography (Tl SPECT) in oral cavity squamous cell carcinoma (SCC). METHODS: Tl SPECTs before and after preoperative radiotherapy were obtained from 11 patients diagnosed with SCC in oral cavity. Regions of interest were set around the tumor and scalp respectively, and the ratio of mean counts in the tumor to those in the scalp was calculated (T/N). Immunohistochemical staining for investigating microvessel density of pre-treatment biopsy specimen was performed using CD31 monoclonal antibody. We compared microvessel density with semi-quantitative parameters obtained using Tl SPECT (T/N at pre- an post-treatment, reduction ratio) and prognosis. RESULTS: The subgroup with higher microvessel density showed a significantly higher reduction ratio than the one with lower microvessel density. Regarding prognosis, the subgroup with locoregional recurrent disease exhibited a significantly higher microvessel density than the one without recurrence. CONCLUSIONS: In SCC of the oral cavity, there was a significant correlation between microvessel density and response to preoperative radiotherapy. Namely, it was revealed that change of 201Tl uptake after preoperative radiotherapy correlated with tumor angiogenesis of oral cavity SCC.
Although 201Tl chloride (Tl) SPECT has been used in the differential diagnosis between recurrence of malignant brain tumor and necrosis after treatment, it is not generally recognized as a definite modality to distinguish them. We conducted a preliminary study using Tl SPECT and 99mTc-MDP or 99mTc-HMDP (Tc) SPECT because it has been said that extraosseous accumulation was caused by calcium deposits in necrotic tissues. In our study, for the purposes of clarifying the mechanism of extraosseous uptake and the correlation between extraosseous accumulation of bone-scanning agent and tumor viability in malignant brain tumors, we compared whether Tc uptake was correlated with the histopathological findings and further performed semi-quantitative evaluation between Tc SPECT and Tl SPECT. The correlation coefficients between the ratio of tumor to normal skull count obtained from Tc SPECT (Tc-T/N) and those of tumor to normal brain count (T/N) and to normal scalp count (T/S) both obtained from Tl SPECT were calculated. Using contrast enhanced CT (CE-CT) or contrast enhanced MRI (CE-MRI), 8 of 10 cases showed intensely ring-enhanced tumor with necrotic lesion. Histopathologically, 7 of 8 cases whose tumor had been resected before treatment had necrosis with increased vascularity or bleeding. Of the remaining 2 cases one case, malignant lymphoma had only hypervascularity by biopsy, while the other one was excluded for resection after treatment. Three of these 8 cases whose CE-CT or CE-MRI showed necrotic lesions exhibited Tc and Tl accumulations in the area corresponding to necrosis. In contrast, 2 showed no Tc nor Tl uptake. Tc-T/N had no significant correlation with any of early-, delayed-T/N or T/S. In conclusion, there was no significant correlation between Tc and Tl uptakes by malignant brain tumors in semi-quantitative evaluation.
The aims of this study were to compare the results of thallium-201 (Tl-201) SPECT, barium swallow and CT in the assessment of the effect of preoperative chemoradiotherapy. This study consisted of 28 patients with advanced esophageal squamous cell carcinoma (AESCC) who underwent the three imaging modalities before and after preoperative chemoradiotherapy. The results were quantified using the bidimensional method for barium swallow and contrast-enhanced CT and the tumor-to-lung ratio for SPECT. The percent decrease in these quantitative values after therapy was defined as %Dba, %Dct and %Dtl respectively. The histological effect of the chemoradiotherapy was determined from the resected surgical specimen of the esophagus: grade 0, 100% viable tumor cells; grade 1a, 99-67%; grade 1b, 66-34%; grade 2, 33-1%; grade 3, no viable cells. A statistically significant difference of %Dtl between the subgroups of each grade was evident (p = 0.0433), whereas no significant differences were evident for %Dba (p = 0.1778) or %Dct (p = 0.7377). However, the overlap of %Dtl between these groups was marked. Although thallium-201 SPECT cannot be used to evaluate the therapeutic effect with acceptable accuracy, SPECT may be of additional value to barium swallow and CT in assessing the response of AESCC to preoperative chemoradiotherapy.
About 20 years ago, gallium-67 planar scintigraphy was introduced for the evaluation of advanced esophageal squamous cell carcinoma (AESCC). Although single-photon emission tomography (SPET) is now available in many institutions, there have been no reports regarding the evaluation of AESCC using (67)Ga SPET. The aims of this preliminary study were to assess the potential of (67)Ga SPET for the detection of AESCC and to further evaluate whether (67)Ga SPET can predict the effect of preoperative chemoradiotherapy on AESCC. Thirty-eight patients with histologically proven AESCC (35 men and 3 women, mean age 62+/-6.9 years) underwent (67)Ga SPET before and after preoperative chemoradiotherapy. The histological response to the chemoradiotherapy was determined from a surgical specimen of the esophagus: grade 0, 100% viable tumor cells; grade 1a, 99%-67%; grade 1b, 66%-34%; grade 2, 33%-1%; grade 3, no viable cells. Thirty-seven out of 38 AESCCs (97.4%) were detected on pre-chemoradiotherapy SPET. In these 37 cancers, the tumor-to-lung ratio (TLRpre) was 3.5+/-2 (range 1.5-9.6). Post-chemoradiotherapy SPET exhibited positive results in 22 cancers, with a TLRpost of 1.8+/-0.4 (range 1.1-2.6). No patient exhibiting a pathologically complete response had a positive post-chemoradiotherapy SPET result, whereas 80% of patients with negative post-chemoradiotherapy SPET (12/15) results had residual tumor. The percent reduction rate was defined as (TLRpre-TLRpost)/TLRpre x100 and did not correlate with histological response grade ( P=0.5169 for Kruskal-Wallis test). These results suggest that (67)Ga SPET is a powerful tool for the detection of AESCC. However, (67)Ga SPET seems to be of little use in predicting the effects of preoperative chemoradiotherapy on AESCC. Further studies are warranted in order to further clarify the clinical usefulness of (67)Ga SPET in patients with AESCC.
BACKGROUND: Controversy surrounds the correct injection site of radioisotope (RI) and blue dye for sentinel node biopsy (SNB) in breast cancer, and there have been some reports on the advantages of subareolar (SA) injection. We carried out a study to assess whether SA injection is useful for all patients undergoing SNB. METHODS: In this prospective study, 20 patients with T1 or T2 tumors clinically node negative, were enrolled. Injection of 99mTc-phytate (0.5 mCi) was performed two times (3 to 5 days before surgery and the day of surgery) for each patient. The first RI injection was SA, and the second RI injection was subdermal (SD). The location and number of hot nodes were assessed by lymphoscintigraphy (LSG) and hand-held gamma probe. RESULTS: There were no patients in whom hot nodes on LSG were visualized in clearly different locations between the SA and SD injection sites. However, there were 2 patients in whom hot nodes were identified at different locations with a gamma probe. Seven patients had more hot nodes on LSG with SD injection than SA injection. Eight patients had a higher RI count of hot nodes by SD injection than SA injection. The mean RI count of hot nodes by SA injection was higher than that after SD injection. CONCLUSION: SA and SD lymphatic flow run into the same node in most patients, however, SD injection is more useful than SA injection in some patients. Though SA injection is a useful technique, it may not identify sentinel lymph nodes correctly in patients with multiple lesions or tumors in the upper outer quadrant.
Although extraosseous accumulations of 99mTc phosphate complexes are phenomena which can often be seen, no case showing extraosseous accumulation to brain tumor on SPECT has been reported. We report here two cases of primary brain tumor showing extraosseous accumulation of 99mTc phosphate in bone SPECT. 201Tl SPECT also showed increased 201Tl uptake by the tumor. Comparing bone SPECT with 201Tl SPECT, the regions of abnormality of both SPECTs were very similar in the case of glioblastoma, but in the case of malignant lymphoma the region showing intense uptake of 99mTc-MDP was smaller than that on 201Tl SPECT. It was revealed that bone SPECT is more useful in the assessment of extraosseous accumulation to a primary brain tumor than conventional bone scintigraphy.
We describe a patient with a final diagnosis of inflammatory change in which combined imaging results were strongly suggestive of lung cancer with mediastinal lymph node metastases. The patient, who was suspected of having a pulmonary lesion on chest radiography performed at a local hospital, was referred to our hospital. Contrast-enhanced computed tomography (CT) of the chest showed a small-sized opacity in the left upper lung and multiple mediastinal nodules. The largest mediastinal nodule, depicted at a pretracheal region, was 22 mm in size. Thallium-201 single photon emission computed tomography (SPECT) showed increased uptake in these lesions, which exhibited no remarkable washout of the tracer, supportive of the diagnosis of lung cancer with mediastinal lymph node metastasis. However, bronchoscopic and mediastinoscopic biopsy revealed no malignant cells or reactive lymph nodes, respectively. Therefore, no surgical procedure was performed after the biopsy. The patient has done well without evidence of malignancy for 21 months. Radiologists should be careful in the differential diagnosis of benign and malignant lesions even with combined imaging modalities.